Precision gyroscope



Aug 3, 1965 J. A. cENcEL 3,198,021

PRECISION GYROSCOPE Filed June '7, 1961 5 Sheets-Sheet 1 Aug. 3, 1965 J. A. cENcEL PRECISION GYROSCOPE 3 Sheets-Sheet 2 Filed June '7, 1961 Aug. 3, 1965 J. A. cl-:NCEL

PRECISION GYROSGOPE 3 Sheets-Sheet 5 Filed June 7, 1961 LA KM #www fabrication of an electrostatically supported gyro.

ever, such efforts have generally been frustrated due to the fact that the magnitude of electrostatic forces required to ,levitate a gyro rotor-and-motor element has been bekryond that possible with apparatus capable of being in- United States Patent O 3,19s,e21 PnncrsroN oraoscoen Joseph Arthur Cencel, Los Angeles, Calif., assigner t0 Litton Systems, Inc., Beverly Hills, Calif. Filed .lune 7, 1%61, Ser. No. 115,379 12 Claims. (Cl. 7d- 5) ythe bearings utilized to rotatably connect the gyro element to its gimbals were an inherent source of gyro error.

More particularly,` the bearings introduce bearing error torques which substantially limit the accuracy of the gyro devices. In addition, the gimbals are themselves an inherent 4source of error in that it is impossible to fabricate a gimbal with suliicient accuracy to insure that the axes defined by the gimbals are aligned with the desired axial directions. Furthermore, the gimbals, like all mechanical pieces, are subject to dimensional variations with temperature so that it is impossible to maintain high accuracy gimbal dimensional stability.

In order to overcome the inherent accuracy limitations of gimbaled gyros, it was recognized that if the gyro rotor element could be levitated and centered by electrostatic means, the use of gimbals and their accompanying bearings could be done away with. In this regard, considerable effort has been directed toward the development and Howcorporated into a gyroscope device.

In an effort to at least reduce somewhat the inaccuracy involved in the use of gimbals and gimbal bearings, a floated gyroscope has been developed in the prior art which allows the use of small size precision jewel-and pivot bearings which serve essentially as loadless guides for guiding the rotor-and-motor assembly with respect f tothe gimbal rather than to support as well as guide the l assembly. More particularly, the gyro rotor-and-motor f assembly is emerged in a flotation iiuid having substantially the same density as the average density of the rotorand-rnotor assembly so that the assembly is floated in f weightless fashion whereby the jewel-and-pivot bearings inability of the bearing to completely isolate the floated element from the gimbal. In addition, foreign matter carried Aby the flotation fluid tends to accumulate in the jewel apertures whereby a sticky mass is produced which impedes the operation of the bearings and results in low gyro sensitivity.

Furthermore, substantial inaccuracy is introduced into the gyro operation as a result of bearing play which affects the linearity of the gyro system.

The present invention, on the other hand, overcomes the foregoing enumerated and other limitations of the 3,1%,ii2l Patented Aug. 3, i965 prior art gyroscope devices by providing a no girnbal iloated gyroscope wherein the gyro floated element is partly supported and maintained centered by means of electrostatic forces. More particularly, the gyro floated element is `substantially floated in a otation iiuid whereby the floated element is substantially weightless. Accordingly, relatively low magnitude electrostatic forces can be utilized to support and orient the floated element.

In accordance with one embodiment of the invention, a plurality of four pairs of pick-off elements positioned around the floated element sense angular and translational deviation of the floated element from its null position and selectively actuate a plurality of three pairs of electrostatic plates connected to the gyroscope housing which exert translational forces on the oated element to return the element to its null position. Detection of angular deviation by the pick-off devices selectively actuates three pairs of torquer elements positioned about the iioated element in such a manner that pure rotational torques are applied to the iioated element along-three mutually orthogonal axes to maintain the floated element in the null position. Accordingly, the iioated rotor-andmotor assembly is maintained properly aligned without gimbal and gimbal bearing structure so that the accuracy of the gyroscope is not limited by the inherent inaccuracy of such structure.

It is, therefore, an object of the invention to provide a floated gyroscope having an electrostatically centered iioated element.

Another object of the invention is to provide a precision gyro wherein bearing error torques are eliminated by partly supporting and by centering a floated rotor-andmotor assembly by electrostatic means.

A further object of the invention is to provide a gimbal less electrostatically centered floated gyroscope having no bearing error torques and which is easily assembled and disassembled.

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which one embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only, and are not intended as a definition of the limits of the invention.

FIG. 1 is an isometric exploded view of a floated gyroscope of the invention;

FIG. 2 is a side view of the case of the gyroscope of FIG. 1;

FIG. 3 is a side cross-sectional view of an exciter coil assembly suitable for use in the present invention;

FIG. 4 is a schematic view of electrical circuitry suitable for use in the present invention; v

FIG. 5 is a cross-sectional fragmentary view of a portion of the outer case of the gyroscope of FIG. 1; and

FIG. 6 is a fragmentary cross-sectional view of two electrostatic pads depicting the manner of mounting the pads to the gyroscope outer ca-se.

Referring now to the drawings wherein like or corresponding parts are referred to by the same reference characters, there is shown in FIG. l, an isometric exploded view of a tioated gyroscope l0 having an electrostatically positioned rotor-and-motor assembly 11 and an XYZ coordinate 1system superimposed thereon. More particularly, rotor-and-motor assembly 11 is floated within a gyro housing made up of a center casing 13, a top cover 14 and a bottom cover i6 by a flotation fluid whose density is such that the rotor-and-motor assembly is near weight- Y no weight. Y

lessness. In accordance with the invention, the near weightless rotor-and-motorassembly 11 1s centered within casing 13 by means of a pair o f diametrically positioned electrostatic' plates or pads 15 and 17,A a similarly positioned pair of pads 19 and 21 and. a pair of electrostatic pads f 23 and 25 diametricallypositioned alongthe ZaxisLon the gyro top cover 14and bottom 16, respectively.

In order to better appreciate the placement ,of theeleci Vshaped low reluctance cores 38,l and 38h-positioned Within a housing 40, each core having a winding wound thereon. Considering now the .operation of the overall plek-off Y unit, the windings wound on cores 38 and 38` are excited trostatic pads 15-21, attention is directed to FIG. 2y where. 'y

in thereis showna side view of'case `1,3.frelative to the XYZ coordinate system Yand an XYTZ coordinate system which is displaced45-in the XY plane with'respect to .the XYZ system. As is indicated in FIG. 2, pads. 15 and of rotor-and-motor assembly 11,isy maintained at some vpredetermined potential, such as ground potential, the

assembly can be'accurately positioned along the Y axis bythe Vapplication of a preselected D.C. voltage" 31 toy '17 are centered along the Y '.axis so that if the outer case either plate 15 or 17 over a pair of conductors 31 and 31',

respectively. In addition; pads r19 `and 21 are centered along the Xt axis so that assembly 11 can be accurately positioned along the X axis by'similarly applying a preselected D.C. voltage 29 to either plate 19 or 21 over af; pair of conductors 29 and 29, respectively.. Accordingly, rotor-and-motor .assembly 11 can be accurately positioned within thegyro housing in the XY'plane'through'the. ac'- tion Aof:electrotatic pads 15,k 17, 19,.and 21.

Referring 'again to FIG. '1, 4as has been mentioned, platesvv 23 and 25 are positioned on opposite sides Of the rotorand-motor assembly 11 and concentric with respectto the by an A.C. signal from an A.C. signal source, to be hereinafterdiscussed, whereby an electromagnetic eld lis de.

veloped which passes between the arms of the cores and hence the pancake coil. Accordingly, an A.C. sensmg signal is induced in the pancake coil whose magnitude and phase is, of course,'determined' by the position of the pancake coil along the axes ATA'.V For example, iftthe center `of they pancake c oilis positioned rnrdw'ay betweenV the twoiarms'of each of theC shaped cores 38 and 38h,

kno resultant signal `will be developed across the pancake coil. However, if the `centervfof the pancake coilmoves along the axes A-.A in the A direction, the magnitude of the signal will be proportional to the departure of the center of the pancakeV coil fromjthe mid-point andthe Vsignal will be in phase-withthe A.C. signal .applied to the excitation-coil;v It, however, lthe pancake coil moves along the A-A axes in the" A' direction, the magnitude of the signal will beiproportional to the movement but the phase of the 'signalY inducedacross the pancake'coil will be ,81810,uw out' of phase with rthe A.C. signal. Accordingly,

Z axis. "Accordingly, by applyinga preselected lD.C.

voltage 33 to either plate 23 or 25 over a pair of contionedfor centered. along the Z'axis. Hence, by the application of preselected voltages 29,131,'and 33 to the elec-- trostatic plates, the rotor-and-motor assembly can be ac- .A curatelycenterejd Within thel gyro housing. In this regard, v t it should be noted that inscontrast to prior art devices, the

voltages needed to center the rotor-and-motor".assembly are relatively small since, due to the operation of the flotaltion fluid, rotor-and-motor assembly 11 hasV substantially As has been heretofore mentioned, the rotor-and-motor assemblyr is centered by Y,applying the preselected voltage .Y signals to the electrostatic lplates or pads. The'magnitudeY and polarityof the voltages of the preselected signalsfare determined in accordance with the deviation of theV rotorand-motor assembly `from its'null or centered' position.

`In this regard, as v'indicated-inFIGSL1 and 2, casing -13 voff the Ygyrcscope'is provided with a number of aperturestherein for receiving a plurality of eight pick-off exciterr coilsj28e, 28,6, 30e; 301 v326,328,l 345 34e,'while rthereV p yare attached to the rotor-and-motor.assembly a'colre# j sponding plurality of pancakesensing coils 28a, 28c, 30C, 30c 32C, 32c, 34C, and 34c, which are positionedfin registry with the eight'exciter coils whenithe .gyroscope is assembled. In the interest of simplicity, all of thepick-Y off and sensing elements are notshownin FIG. 1v but are included in FIG. 4, to be hereinafter discussed.z` The eight exciter .and sensing coils Acomprise aplurality of eight ini dividual pick-oli" units 28.thr'ough S14-which, as willbe hereinafter explained. are operable to generate sensing `Y Y. vsignals which represent the translational as Well as'angular deviation of the rotor-and-motor assembly relative. to the null position. A v

Directing attention now ,to the structurel andv operation the phase of the A.C. signal is indicative of the direction of'movement of'rthe rotor-and-motor .assembly Yand the magnitude of the signaljis representative :of the movement of the rotor-and-motor assembly.

f Continuing'with the discussion' of the inventiomrthere is shown in FIG. 4 a servo circuit 27 ywhich operates onthe sensing signals Ato generate preselected D.C.'signals 29, 31,

Iand 33,`wl1ose voltages arerelatedfto the translational dis- `ductors 33 and 33', respectively, assembly 11 can be posiassembly'is returned to its null position.

Y', and,y Z axes, respectively, ins'uch a manner that upon application to the ,electrostatic pads, the rotor-and-motor Circuit 27 is .also responsive to the vsensing 'signals from the pick-olf units to generate three A.C. torquing signals 35, 37,l and 39 which Vrepresent the angular deviation `of rotor-and- -motor assembly about the Y, Z, and X axes, respectively. Referring now` to FIG. 5, there is shown a cross-sectional Yfragmentary view`ofcasing13 and electrostatic pad 15 depicting themannerof mounting the four pads 15-21 tocasing'13. As is shown in' FIGrS, pad'15 is mounted tothe `casing by means of a non-conductive jewel. Asis further-shown inf-FIG, 5,'the` radialpositioning` of the pad can be changedfrom. the exterior ,of casing 13` by j ltionalviewdepicting ther manner of mounting these pads to covers 14and 16. As is shown in FIG. 6, andas furmeans of screw 81'. v l Referring now to pads 23 and 25, attention is directed to FIG.v 6 wherein vthere is fshown a fragmentary cross-secther indicated in FIG. Leach of the pads are mounted to `their respective ycovers;by three non-conductive cylindrical jewels. As isfurther indicated in FIGS. 6 and l, a leaf/spring `83 isnterp'osition'ed between pad23 .and

` cover 14'in order to facilitatethe positioning of the pads.

In this regard, it should be noted that the radial spacing ofthe-pads is extremely importantV since the distance p betweenthe padjsurface and the grounded surface of the rotor-and-motorrassembly determines the magnitude of f the forces exerted on-the rotor-and-motor assemblyv for vany predetermined potential.

v While numerousv methods can'be used tocorrectly positionthe electrostatic pads, one suitable method is to place a positioning ball vwitlrinrthe gyroscope assembly `rather f than the rotor-andmotorjassernbly, thev positioning ball having a radius greater than the 'rotor-and-motor assembly by thedesired'spacing betweenfthe padand the surface of y' the ,rotor-.and-motor assembly. VBefore A the positioning ballis placed within the gyru, kthe area Vbehindthe pads :should be lilled with some'fsuitable adhesive material such f aszan epoxy resin sothat when lpads 15f21 arefpositioned against the positioningk ball, by turning screw 81, the resin invention are Well known to those skilled in the art.

this regard, one especially suitable torquer is disclosed February 26, 1963 .by Bruce A. Sawyer.

' static pads to eliminate the translational deviation.

' addition, the servo circuit generates the A.C. torquing signals which are applied to the torquing coils of the torquers will harden and the pads will be permanently positioned. As is shown in FIG. l, pad 25 can be externally forced against the surface of the positioning ball through the aperture in cover 16. However, since pad 23 cannot be reached after assembly from outside the case', leaf spring 83 is used to force the pad against the positioning ball. It should be noted in this regard that leaf spring 83 snould beso chosen that its spring force is not great enough to Overcome the adhesive forces produced by the hardened resin.

As is apparent, after the adhesive resin has cured or hardened, the positioning ball is removed and the rotorand-inotor assembly positioned in the gyro whereby all of the pads will be correctly and permanently positioned.

Continuing further with the discussion ofthe invention, gyro vfurther includes a plural-ity of three pairs of torque-rs 41 and 41', 43 and 43', and 45 and 45', which are responsive to torquing signals 35, 37, and 39 tor torquing rotor-and-motor assembly 11 about the XYZ axes lto cancel 4out 'the deviation. Accordingly, the' spin axis is maintained oriented along the X axis and assembly 11 can be oriented in any desired angular orientation along the Y and Z axes.

It y.should be noted in connection with torquing the rotor-and-rnotor assembly that 'while a torquing force couple applied about the X axis (spin axis) will cause the rotor-and-inotor assembly to rotate about the X axis, aS

is well known to one skilled in the art, torquing the rotoryand-motor assembly about the Y axis will result in rota- -tion of the assembly about the Z axis. lFurther, torquing the .assembly abouty the Z axis `wil-l result in rotation of the assembly about the Y axis. Accordingly, torquing signals 35, 37, and 39 should be applied to torquer coils 45 and 45', 43 and 43', and 41 .and 41', respectively, each of the toi'quer coil pairs 41 and 41', 43 and 43', and 45 and 45' ybeingwound in opposite directions so that one exerts a pushing force on one side of rotor-and-niotor assembly 11 while the other exerts a pulling force on the other side .so `that a pure force couple is applied to the assembly.

In connection with a detailed discussion of the structure l of the torquers, it should be noted that numerous diffe-ring types of torquer structures suitable for use with the present In .in U.-S. lPatent now Patent No. 3,078,723 entitled, Miniaturized Temperature Insensitive Accelerome'ter issued Accordingly, the torques disclosed in FIGS. 1 and 2 are of the Sawyer i type.

' magnets and coils tit in register with one another when rotor-andamotor assembly 11 is positioned Within casing 13.

In view of the foregoing, it should be clear that the pick-ott units detect angular and translational movement of the lrotoiand-motor assembly from the null position and transmit signals representative of such displacement to .servo circuit 27. Servo circuit 27 then generates the preselected D.C. signals which are applied to the electro- In lfor torquing the rotor-and-motor assembly to eliminate A any angular displacement of the rotor-and-rnotor assembly -voltages generated .by the pick-offs are dictated by the following equations:

Where L1, L2, a, and b are the respective lever arms of the pick-offs, KZS through K3., are const-ants of proportionality `and 0x, y, and HZ are the angular deviations of the rotor-and-motor assembly about the X, Y, and Z axes, respectively.

As is apparent from the foregoing equations, the sum of the voltage signals from pick-offs 30 and 30' is proportional to the angular deviation of the rotor-and-motor assembly about the Z axis. 'In addition, it is clear that the summation of the voltages generated Eby pick-oils 28 and 28' and 32 rand 32' are proportional to the angul-ar deviation of rotor-and-motor assembly 11 about the Y and X axes, respectively. Furthermore, by properly combining equations 1 through 6 and -8, it can :be shown that voltages proportional to the translation of the rotor-andmotor assembly along the X', Y and Z `axes are given by the following equations:

Referring now with particularity to servo circuit 27, as is shown in FIG. 4, the servo circuit includes a logic circuit 47, a gating circuit 49, a rectifying circuit 511, a transformer circuit 48, and .an A C. signal source 53. As iS apparent from an examination of .FIG. 4, logic circuit 47 includes conventional analog circuitry for mechanizing Equations 9, yl() :and l1 to produce signals VX', Vy', and VZ as well as three individual ampli-tiers 52, 54, and Safor .amplifying Vx', Vy', and VZ, respectively. -In addition, logic circuit `47 includes circuitry for summing V30 and V30' to produce A.C. torquing signal 37, V28 and V28' to produce torquing signal and V32 and V32' to produce torquing signal 89.

Continuing with the discussion of the invention, as 1s shown in FIG. 4, the A.C. voltage signals VX', VY', and VZ are applied to gate 49 along with the AiC. excltation signal from source l53 which, as has been heretofore mentioned, is applied to and used to excite the piekof exciter coil. The gating circuit compares the phase of the AiC. voltage signals from logic 'circuit 47 'with the phase of the excitation signal from source 53 yand directs signals VX', Vy', and VZ over conduct-ors 29 or 29', 31 or l31 .and 33 orw33', respectively, in accordance with whether the signals are in phase or 180 out of phase with the excitation signal.

More particularly, as is shown in FIG. 4, gating circuit 49 includes a plurality of three pairs 'of gates 53, and 53h, SSZ and 551 and 57 and 571,. The A.C. signal from the AiC. signal source is applied directly to gates 531 h, and 57 while the A.C. signal is applied to inverter 59 before being applied to gating .circuits 53a, 55a, and 57 so that an inverted A.C. signal is applied to these gating circuits.

As is further shown in FIG. 4, Vx, Vy', and VZ are applied to gating circuits 53a and 53h, and 55a and 55h and, 57a and 571 respectively. Accordingly, since the gating circuits operate .as basic and gates, if the signals from logic circuit 47 are in phase with the A.C. signal from by the a series gates. In this manner, signals VX, Vy', and Vz are directed to the appropriate electrostatic pads to exert forces on the rotor-andmotor assembly forV rc- Y turning the .assembly to its null position.

I. source Se, they will :be passed by'onejof the b series gatesV I while if they are 180 Y out of phase, they would be vpassed V.Asshown in FIG. 4, the gated signals from logic cir- Y cuit 47 are then applied to voltage .step-'up transformers within transformer Vcircuitry 48 whereby the maximum.

peak-to-peak voltage ofrthe gatedvsignals is increased to -a sufiicientvoltage to y insure that 'theHr-fotor-and-motor assembly will' be returned toits` null position., j'lhe stepped-up voltage signals are then applied to'rectifymg circuit 51 and rectiied to takefa substantially D.C. form Vwhereby they are 'then'applie'd directedto the appropriate electrostatic pads.

y Continuing with the discussion of the invention; it

should be pointed out Vthat a'flarger magnitude Voltage y generally needs to be applied. tothe electrostatic pads when the-'gyr'o is initially turned on, than is required during normal operation. This isV true since'during the initial turn-on, the gyro isgenerally substantially removed from the centeror `null position 'anda considerable'force is required to retain it to the null'position along the ,axes aligned with the gravity vector. I i v In' this regard, it should be noted that if Vitl isdesired to mechanize the gyroscope of theinvention in such .a manner that rrelatively small magnitudeyvoltages canv be utilized, a dotation fluid should be selectedv having a density within the range' `ot the external gyro environ# said iiuid Vdisplaced'iby said rotor=andmotor wassembly to cancelV the rotation and'a'second 'pair of pick-off and 'torquerunits for sensing rotation of said assembly about said secondaxis and for torquing said assembly to cancel the rotation.V Y

6.,The combination defined: in `claim ywherein said f pick-nii and torquer meansffurther includes a'third pair of pick-oif;and torquer u nits for sensing rotation of said kassembly about said spinaxis and for applying a ltorque to said assembly for nulling rotation aboutjsaid spin axis.

7. 'In a yprecision gyro, Vthe combination comprising; a gyro housing; aY substantially spherical rotor-and-motor assembly, said assembly positioned 'within said housing;Y and having a spin axisgfmeansgfor supporting said assembly free from physical support contact by the housing, said means includinga iiotation j fluid surrounding Y rsaid rotor-and-motor-assembly; Vandv including additional mental temperature that is'substantially greater than that of the rotor-andmotor assembly, but which is somewhatYV Y less than that of the rotor-and-motor assembly Vwhenthe fluid is heated by'the constant application of the elec-AY trostatic voltages to the electrostatic pads during the initial centering. Accordingly, the rotor-and-motor assembly Will sink'past'the center .or null position and thereby lock into position without the necessity of a largeY electrostatic potential. l

Itshould also benoted that thegyroscope of the ini vention can be modifedin Vmany particulars as canlthe servo circuit. For example, the servo circuit can rbe mechanized so that ratherpthan applying a valtage lto only one of each pair of electrostatic pads', a Voltage is applied simultaneously to all pads. Accordingly, the scope'of the invention is to be limited only by the spirit and scope of the appended claims.

What isl claimed as new is: l Y Y y 1. In a precision gyro, the 'combination comprising:

Va housingrm'ernber; a 'substantially spherical',rotor-and-` motor assembly positioned within Vsaid housing member, 'said assembly having as spin axis; a otationliquid illing said housingr member and surrounding said "rotor-andmotor assembly, the mass of theliquid displaced lby said rotor-and-motor assembly being"approximately"equalto the mass of said assembly; electrostatic `means for electrostaticallyV positioning 'said assembly in said housing; l l and torquer means selectively operable to kapply,Y force couples ftosaid rotor-and-motor assembly for precessing p said'rotor-and-motor assembly.v

z. vThe combinati@ defined m 1anniwhe'ni said' electrostatic means includes a pair of diametrically'opposed electrostatic plates positioned on said housing.

' assembly.

means exerting ay levitation'force lon the assembly, and tor'- quer means selectivelyloperable for applyingforce cou- 30 -sembly about said spin'axes to maintain: said spin axes plestosaid rotor-and-motor assembly to rotate said asaligned in a predetermined direction.:

`811m a precision-gyro, the combination comprising: a

housing member; a rotor-and-motor assembly positioned within said housingumember, sai-d assembly'having a spin axis; means for supporting said assembly free from `physical support contact by the'housing, said means including a flotation liquid lling said housing memberand surrounding said rotorfand-motor assembly, the massgof the liquid displaced by said rotor-andmotor assembly bef ing approximately equal to theimass'of said assembly; and

vincluding additional meansexerting a levitation` Vforce yon the assembly, pick-off meansr positioned adjacent said rotor-and-motor assembly for Ygenerating Va signal representativeof'thef magnitude and .direction ot the rota- Qtion of said rotor-and-motor assembly about said spin axis; and .torquer means positioned adjacent said rotorand-motor, assembly responsive to said signal for applyof rst and second mutually. orthogonal axes; a'otation 3. The combination dened in :claim 2l wherein said Y electrostatic.meansffurther include two additionalpairs of electrostatic plates, each pair ofv 'plates'bemg posi- Y tioned onthe inside surface of said yhousing -diametrically opposed 'relativerto said rotor-and-rnotor assembly. .4. UInj aV precision two-pde'gree-lof-freedom gyr o,the combination comprising: ahousingjrnemberg a sphericalV ro-y tor-andrnotorI assembly. positioned withinsaid' Ihousing member, said Yassembly having la spin axis orthogonal to a pairof firstv and-secondv mutually orthogonal'sensing axes; a flotation uidhillingrsaid housing member and p surrounding said -rotor-and-motor assembly, ytherri'ass `of ing a torque to said rotor-and-motor assembly about said spin axis to null out the rotation of said rotor-and-motor 9. In a precision two-degree-of-freedon`1` gyro, the cornbinaton-comprising: a housing member; a spherical rotorand-motor assembly positioned within saidr housing member, said assemblyhayingv a spin axis orthogonal'to a pair uid filling said housing member and surrounding said rotor-and-'motor assembly, the mass of said tiuiddisplaced by said Vrotor-and-motor .assembly being `approximately equal to Vthe mass of said assembly; pick-olf ,means for sensing rotation of'said rotorand-motor assembly about said irst,second, land spin faxes .from;f-a.predetermined angular orientation and for Ysensing-translational move ment of said rotor-and-motor assembly'from a null-position;V a servo circuit1coupled to said pick-off vmeans and operable vfor generating first, 'secon'd, and 4third signals rep- 'resentative of the translational movement of saidrotorand-'motor assembly along said riirst, second, and spin axes,

if respectively,'said servo means being yfurther operable'for j generating fourth,'fth, and sixth Vtorquing signalsrepre- 'f sentatiyeV ofthe magnitude' of the 'rotation'l of saidrotorand-motor'assernbly about said iirst, second, and spinr axes,

respectively; rst electrostaticY means positioned on said housing Yand responsive to saidiirstV signal for generating an electrostatic field exerting'a force on'saidrotor-andmotor assembly tending to cancel out the translational movement of said rotor-and-motor assembly along the irst axis; second electrostatic means positioned on said housing adjacent said rotor-andmotor assembly and responsive to said second signal for generating an electrostatic field exerting a force on said rotor-and-motor assembly tending to cancel out the translational movement or said rotorand motor assembly along the second axis; third electrostatic means positioned on said housing adjacent said rotor-and-motor assembly and responsive to said third signal for generating an electrostatic iield exerting a force on said rotor-and-motor assembly tending to cancel out the translational movement of said rotor-and-motor assembly along the spin axis; torquer means coupled to said servo circuit and positioned adjacent said rotor-and-motor assembly for torquing said rotor-and-motor assembly about said rst, second, and spin axes in accordance with said fourth, fth, and sixth signals, respectively, to cancel out the angular rotation oi said rotor-and-motor assembly whereby said rotor-and-motor assembly is maintained in said predetermined angular orientation.

lil. The combination defined in claim 9 wherein each of said first, second, and third electrostatic means includes a pair of first and second electrostatic pads positioned on opposite sides of said rotor-and-motor assembly along said first, second, and spin axes, respectively.

ll. The combination deined in claim lil wherein said servo circuit is connected to each of said first and second electrostatic pads and includes gating elements for selectively applying said first, second, and third signals selectively to one or the other of said lirst and second pads of said rst, second, and third electrostatic means, respectively.

12. ln a precision gyro, the combination comprising: a housing member; a spherical rotor-and-motor assembly positioned within said housing member, said assembly having a spin axis orthogonal to a pair of first and second mutually orthogonal axes; a dotation tluid lling said housing member and surrounding said rotor-and-motor assembly, the mass of said iluid displaced by said rotor-and motor assembly being approximately equal to the mass of said assembly; lirst, second, and third pick-ofimeans positioned adjacent said rotor-andmotor assembly and operable or generating first, second, and third sensing signals, respectively, said first, second, and third sensing signals being representative of both the rotation from a predetermined angular orientation of said rotor-and-motor assembly about said iirst, second, and spin axes, respectively, and the translational movement of said rotor-and-motor assembly from a null position along said lirst, second, and spin axes, respectively; a logic circuit coupled to said first, second, and third pick-oil means, said logic circuit operating on said iirst, second, and third sensing signals to produce fourth, fifth, and sixth torquing signals representative of the angular rotation of said rotor-and-motor assembly about said first, second, and spin axes, respectively, said logic circuit further including apparatus to produce fourth, fifth, and sixth centering signals representative of the translational movement of said rotorand-motor assembly about third, fourth, and spin axes, respectively, said third and fourth axes being in the plane defined by said first and second axes and being displaced therefrom by a predetermined angular increment; first, second, and third electrostatic means responsive to said fourth, fifth, and sixth centering signals for forcing electrostatically said rotorand-motor assembly along said third, fourth, and spin axes, respectively, to return said rotor-and-motor assembly to the null position; and torquing means positioned adjacent said rotor-andmotor assembly and responsive to said irst, second, and third torquing signals for torquing said rotorandmotor assembly about said first, second, and spin axes to return said rotor-and-motor assembly to the predetermined angular orientation.

References Cited bythe Examiner UNlTED STATES PATENTS 2,933,925 4/60 Singleton et al. 74-5 X 3,003,356 10/61 Nordsieck 74-5 BROUGHTON G. DURHAM, Primary Examiner. 

1. IN A PRECISION GYRO, THE COMBINATION COMPRISING: A HOUSING MEMBER; A SUBSTANTIALLY SPHERICAL ROTOR-ANDMOTOR ASSEMBLY POSITIONED WITHIN SAID HOUSING MEMBER, SAID ASSEMBLY HAVING AS SPIN AXIS; A FLOTATION LIQUID FILLING SAID HOUSING MEMBER AND SURROUNDING SAID ROTOR-ANDMOTOR ASSEMBLY, THE MASS OF THE LIQUID DISPLACED BY SAID ROTOR-AND-MOTOR ASSEMBLY BEING APPROXIMATELY EQUAL TO THE MASS OF SAID ASSEMBLY; ELECTROSTATIC MEANS FOR ELECTROSTATICALLY POSITIONING SAID ASSEMBLY IN SAID HOUSING; AND TORQUER MEANS SELECTIVELY OPERABLE TO APPLY FORCE COUPLES TO SAID ROTOR-AND-MOTOR ASSEMBLY FOR PRECESSING SAID ROTOR-AND-MOTOR ASSEMBLY. 